Solar photovoltaic -commercial electricity dually driven heat pump system with cold/heat storage

ABSTRACT

A hybrid-driven cold/heat storage type heat pump unit utilizing a solar photovoltaic power and a commercial power, which has a DC compressor ( 2 ) and an AC compressor ( 8 ), is a dual supply heat pump system driven by a solar photovoltaic DC power and a common commercial AC power in combination. When there is sunshine, the DC generated by a solar cell panel ( 60 ) is used for driving the DC compressor ( 2 ) directly to produce cold and heat capacity, and the produced cold and heat capacity could be stored respectively in a phase-change cold storage medium ( 39 ) and a phase-change heat storage medium ( 20 ). When the DC power is insufficient, the AC power from power network is used for power supply.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from PCT application no. PCT/CN2010/070200, filed Jan. 15, 2010, which in turn claims priority from Chinese application no. 200910076400.X, filed Jan. 15, 2009.

FIELD OF THE INVENTION

The present invention relates to a heat pump system, and more particularly relates to a dual-power-source heat pump system with hybrid driving by a solar energy photovoltaic DC power and an ordinary commercial power.

BACKGROUND OF THE INVENTION

The energy-saving effect of a heat pump type water heater is remarkable. Since a heat pump type water heater has an coefficient of performance (COP) greater than 1, it can generate 3-4 kW heat for water by only 1 kW of electrical power it consumes, so it has a more remarkable energy-saving effect as compared with an ordinary electrical water heater. Moreover, a cold and hot water system with heat pump (water cooling type refrigerator) can produce cold water by producing hot water, and the hot water it produces can be used for domestic water or for heating, while the cold water can be used for air conditioning, so it is expected to be a core device of a future family central energy system and will be of significance to improvement of people's life quality.

A typical solar water heater is a device that collects energy of sunlight using plate heat collector, vacuum tube heat collector, or etc. to heat cool water. It can not produce cold water while producing hot water. Moreover, although solar energy is clean energy of endless supply, it is intermittent and whether-dependent and can only be effective during sunny daytime, it is not applicable in cloudy day or at night, when hot water is mostly needed.

The common existing solar photovoltaic power driven vapor compression refrigeration system makes use of DC-to-AC inverter, that is, it raises voltage of the DC provided by a solar cell panel in the first place, then converts the DC into AC, and then drives an AC compressor with the AC power; however, an inverter is expensive and sophisticated, resulting in increase of the cost of the system.

SUMMARY OF THE INVENTION

An aim of the present invention is to provide a solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage, which can be dually driven by a solar photovoltaic power source and ordinary commercial power source.

The aim of the present invention is achieved by the following technical solution. The solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage according to the present invention comprises: a compressor module, which includes a DC compressor sub-system; a photovoltaic DC power source sub-system, which is coupled to said DC compressor sub-system; an air source condenser; a throttle device; an air source evaporator; a heat storage sub-system coupled between said compressor module and said condenser and containing heat storage phase change material for absorbing heat from refrigerant; a cold storage sub-system coupled between said throttle device and said evaporator and including cold storage phase change material to be refrigerated by said refrigerant; said compressor module, said heat storage sub-system, said condenser, said throttle device, said cold storage sub-system, and said evaporator form into a loop by pipes, with refrigerant circulating within said loop.

Preferably, said compressor module further comprises an AC compressor sub-system connected in parallel with said DC compressor sub-system.

According to an embodiment of the invention, four solenoid valves are provided in said compressor module for controlling the states of the AC compressor of said AC compressor sub-system and the DC compressor of said DC compressor sub-system connected in the refrigerant circulating loop.

According to an embodiment of the present invention, said heat storage sub-system comprises a heat storage container having good thermal insulation and containing heat storage phase change material therein; said cold storage sub-system comprises a cold storage container having good thermal insulation and containing cold storage phase change material therein. Said heat storage sub-system can further comprises: a first coil heat exchanger arranged inside said heat storage container and connected in said refrigerant circulating loop, for allowing heat exchange between refrigerant in it and said heat storage phase change material.

According to an embodiment of the present invention, those arranged in the refrigerant circulating loop include: a first solenoid valve, for bypassing the refrigerant so the refrigerant does not go through the air source condenser; a second solenoid valve, for bypassing the refrigerant so the refrigerant does not go through the air source evaporator; a third solenoid valve, for bypassing the refrigerant so the refrigerant does not go through the heat storage sub-system; and, a forth solenoid valve, for bypassing the refrigerant so the refrigerant does not go through the cold storage sub-system.

Preferably, a first temperature sensor is provided in the heat storage sub-system for detecting the temperature of the heat storage phase change material in order to determine whether to open or close the first and the third solenoid valve; and, a second temperature sensor is provided in the cold storage sub-system for detecting the temperature of the cold storage phase change material in order to determine whether to open or close the second and the forth solenoid valve.

In the solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage, the heat storage phase change material can be one selected from paraffin, hydrated salt, and sodium sulfate decahydrate, while the cold storage phase change material can be one selected from glycerol, water, hydrated salt, and paraffin.

According to an embodiment of the invention, the photovoltaic DC power source sub-system comprises a solar cell assembly, a junction box, a storage battery, and a power and voltage regulator.

According to an embodiment of the invention, a high pressure sensor is provided in the high pressure pipe line of the heat pump system, a low pressure sensor is provided in the low pressure pipe line, and a safety valve is provided in the heat storage sub-system and the cold storage sub-system respectively.

The main advantageous effects of present invention includes:

The solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage has dual compressors, a DC compressor and an AC compressor, which are complementary to each other. When sunlight is present, the DC refrigeration compressor is driven directly by DC current generated by solar cell panel to produce cold and heat, the produced cold and heat can be stored by phase changed material (PCM) respectively so as to remedy the disadvantage that solar energy is intermittent and whether dependent. When the DC current is insufficient, AC power from commercial power grid is used to supply power, thus the flexibility of the system is greatly enhanced. Moreover, two refrigeration compressors are provided in the present invention: a DC compressor and an AC compressor; when solar energy is adequate, the AC compressor does not operate; when both the solar energy and the stored energy are inadequate, the AC compressor is connected to commercial power grid for replacing the DC compressor. It can be seen from above that the power load of air conditioning is shared by compressors driven by solar energy and commercial power source at different time intervals, and the ratio of loads to be carried by the DC compressor and AC compressor can be properly set according to requirements on cost, thus greatly lowering the initial cost of solar air conditioning system and enhancing the applicability of the system.

The phase change energy storage device provided in the present invention stores hot water and cold water produced by heat pump, so an allocation can be made between the time intervals of collecting solar energy and those of consuming solar energy, and an allocation can be made between the high production rate of cold/hot water and low amount of consumption by the users, to allow efficient utilization of solar energy and avoid unnecessary waste.

Comparing with existing solar water heaters, in the present invention, solar energy and heat pump water heater systems are combined so cold water is produced at the same time hot water is produced. In the present invention, solar photovoltaic cell panel is used to generate DC power, whose voltage is then raised and power regulated to drive a vapor compression refrigerator unit; hot water is produced at the condenser side of the refrigerator, while cold water is produced at the evaporator side of the refrigerator. With such an apparatus, we can get free cold water and hot water with the aid of sunlight, that is, enjoy free domestic hot water and air conditioning with the investment of the apparatus. When heat or cold storage reaches its limit, heat is dissipated by the air source condenser or by the air source evaporator.

Comparing with existing solar photovoltaic vapor compression refrigerator system, the system of the present invention needs no DC-AC converter while the area of solar cell panel can be greatly reduced due to a shared load mechanism of power. The system of the present invention overcomes the limit of solar energy while it makes a full use of solar energy, and it has remarkable cost advantage.

DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows the structure of an embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

The technical solution of the present invention is described in detail with reference to accompanying drawings.

The main body of the solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage is a heat pump system; cold water can be produced at the evaporator side of the heat pump system while hot water can be produced at the condenser side of it. Cold and heat energy is stored by phase change materials respectively to eliminate the conflict of the difference between operation time interval of the heat pump system and the usage time interval of cold/hot water. The core part of the heat pump system includes two complementary compressors, a DC compressor and an AC compressor. The DC compressor operates with the DC power generated by the solar photovoltaic system, while the AC compressor operates with the commercial AC power.

As shown in FIG. 1, an embodiment according to the present invention comprises a DC compressor sub-system A, an optional AC compressor sub-system B, a heat storage sub-system C, a air source condensor D, a fluid storage device E, a dryer filter F, an expansion valve or throttle device G, a cold storage sub-system H, a fin evaporator I, and a photovoltaic DC power source sub-system K. The connection relationships in such an embodiment is that sub-systems A and B are connected in parallel, and that the parallel-connected sub-systems A and B are connected by pipe lines with sub-systems C, D, E, F, G, H, and I to form a closed loop, in which refrigerant circulates. An AC power supply sub-system J is connected by wire to a junction box of AC compressor sub-system B. The photovoltaic DC power source sub-system K is connected by wire to a junction box of DC compressor sub-system A.

DC compressor sub-system A comprises a DC compressor 2, a solenoid valve 1 arranged on the exhaust pipe of DC compressor 2, an solenoid valve 3 arranged on the air intake pipe of DC compressor 2.

AC compressor sub-system B comprises an AC compressor 8, a solenoid valve 7 and a tee joint 6 arranged on the exhaust pipe of AC compressor 8, a solenoid valve 9 and a tee joint 10 arranged on the air intake pipe of AC compressor 8.

Heat storage sub-system C comprises a container (heat storage tub) 17 having good thermal insulation, a safety valve 18, a temperature sensor 19, phaseheat storage phase change material 20 contained in the heat storage tub 17, a hot water outlet valve 21, a hot water return valve 22, a coil heat exchanger 23, a refrigerant outlet valve 24, a refrigerant inlet valve 25, a coil heat exchanger 26, a tee joint 27, a bypass solenoid valve 28, and a tee joint 29. The temperature sensor 19 is provided at the top of the heat storage tub 17.

Bypass solenoid valve 28 is provided on the inlet and outlet pipes of the heat storage sub-system and is normally closed.

Air source Condenser D comprises a blower 33, a fin-tube heat exchanger 34, a tee joint 30, a solenoid valve 31, and a tee joint 32.

Cold storage sub-system H comprises a container (cold storage tub) 38 having good thermal insulation for containing cold storage phase change material 39, a refrigerant outlet valve 40, a refrigerant inlet valve 41, a temperature sensor 42, a coil heat exchanger 43, a cold water return valve 44, a cold water outlet valve 45, a coil heat exchanger 46, a safety valve 47, a tee joint 35, a bypass solenoid valve 36, and a tee joint 37. Temperature sensor 42 is arranged at the lower end of cold storage tub 38.

Bypass solenoid valve 36 is provided at the inlet and outlet pipes of the cold storage sub-system and is normally closed.

Air source evaporator I comprises a blower 52, a fin-tube heat exchanger 51, a tee joint 48, a solenoid valve 49, and a tee joint 50.

AC power supply sub-system J comprises an AC junction box 55 and wire 54 connecting to AC compressor 8.

Photovoltaic DC power supply sub-system K comprises a solar cell assembly 60, a junction box 59, a storage battery 58, a power and voltage regulator 57, and wire 56 connecting to DC refrigeration compressor 2. These parts are connected by wires as shown in FIG. 1. Photovoltaic DC power supply sub-system K is for receiving sunlight to generate DC power supply for operation of DC refrigeration compressor 2.

At the initial equilibrium state with respect to room temperature, heat storage phase change material 20 in heat storage tub 17 is in solid state, while cold storage phase change material 39 in cold storage tub 38 is in liquid state.

A thermal characteristic of heat storage phase change material 20 is: while it is in solid state at an initial temperature, when it is heated to its melting point, it begins partly melting and stays in a solid-liquid mixture state, and its temperature keeps substantially unchanged in this state, until it is wholly changed into liquid. Only then will its temperature raise further if it is heated further. Heat storage phase change material 20 can be paraffin, hydrated salt, and sodium sulfate decahydrate, or so on, which has such characteristic.

A thermal characteristic of cold storage phase change material 39 is: while it is in liquid state at an initial temperature, when it is cooled to release heat and its temperature is lowered to its freezing point, it begins to partly solidified and stays in a solid-liquid mixture state while its temperature keeps substantially unchanged in this state, until it is wholly changed into solid state. Only then will its temperature drop further if it is cooled further. cold storage phase change material 39 can be glycerol, paraffin, hydrated salt or the like.

According to the above embodiment, a heat pump system of the present invention is supplied with power by solar photovoltaic DC power supply sub-system. The solar cell panel comprises a plurality of solar cell assembly 60 connected in series and in parallel in a predetermined manner to meet preset voltage and current requirements. The photovoltaic power supply is connected to junction box 59, and supply power to DC compressor 2 after power regulation and voltage stabilization by power and voltage regulator 57. When DC compressor 2 is not on duty, surplus electrical energy can be stored in storage battery 58.

DC compressor 2 is driven by DC power supply. The direction of the refrigerant circulation is: refrigerant in the system sequentially goes through A→C→D→E→F→G→H→I→A. At this time, solenoid valves 1 and 3 are in their opened state under control of the system controller, solenoid valves 7 and 9 are in their closed state under control of the system controller, wire 56 is in connected state, while wire 54 is in disconnected state. In this mode, AC compressor 8 and DC compressor 2 do not work at the same time.

Refrigerant vapor is compressed by DC compressor 2 into high-temperature and high-pressure vapor, then it heats heat stroage phase change material 20 through coil heat exchanger 23. With its rise in temperature, heat stroage phase change material 20 undergoes phase change from solid to liquid, while the refrigerant vapor is partially cooled. After heat stroage phase change material 20 is heated, it can functions as a heat source for transmitting heat to coil heat exchanger 26 to supply hot water to outside.

The partially cooled refrigerant vapor then enters air source heat exchanger 34 to be cooled further; its heat of condensation is carried away by airflow by condenser blower 33 and is dissipated into the atmosphere. At the outlet of condensor D, all of the refrigerant vapor is converted into liquid.

Then, the refrigerant liquid is allowed to pass fluid storage device E and dryer filter F to arrive at throttle device G. Fluid storage device E functions to adjust the circulation amount of refrigerant in the system against variation due to cold/heat load so as to ensure that the pressure flunctuation in the system is not too great. Dryer filter F functions to filtrate impurity in the circulating refrigerant to keep the system clean and to absorb water in the refrigerant to prevent it from freezing to clog the throttle device.

The expansion valve or throttle device G can be a capillary, a thermostatic expansion valve, an electronic expansion valve, or an orifice control valve.

After the refrigerant liquid is throttled by the throttle device G, its pressure is lowered, and it partly transforms into flash vapor and its temperature is also lowered, and it changes into a vapor-liquid mixture. The vapor-liquid mixture of refrigerant enters into coil heat exchanger 46 in cold storage tub 38 and air source evaporator I in sequence and absorbs heat. At the outlet of the air source evaporator I, the refrigerant is completely transformed to vapor, which then enters into DC compressor 2 to begin the next cycle.

Cold storage phase change material 39 in cold storage tub 38 is frozen so that phase change from liquid to solid happens. After cold storage phase change material 39 is frozen, it can be used as a cold source for transmitting cold to coil heat exchanger 43 and to supply cold water to outside.

Of the two compressors, AC compressor 8 is ordinarily a backup. When DC compressor 2 cannot work due to insufficient DC power supplied by solar sub-system K, AC compressor operates to replace DC compressor 2. Then, the power supply of AC compressor 8 is from AC junction box 55, while the current of AC junction box 55 is from commercial electricity grid. When AC compressor 8 operates, the flow of refrigerant is: refrigerant in the system flows sequentially B→C→D→E→F→G→H→I→B. At this time, solenoid valves 7 and 9 are opened under the control of system controller, solenoid valves 1 and 3 are closed under the control of system controller, wire 54 is connected, and wire 56 is disconnected.

Both heat storage sub-system C and air source condenser D supply heat to the outside and carry the heat load of the heat pump system, so these two sub-system can work either at the same time or not. When solenoid valve 31 is opened under the control of a controller, refrigerant is bypassed to move directly from tee joint 30 to tee joint 32 without passing the fin-tube heat exchanger 34 (since its pipe is relatively long, resistance is great correspondingly; if the resistances in the two pathways do not differ very much, an additional solenoid valve can be provided at the inlet of the fin-tube heat exchanger 34 to completely cut-off this pathway;) at this time, air source condensor D does not work and it is not necessary for blower 33 to operate.

The time at which air source condensor D begins to operate can be determined by the temperature of heat storage phase change material 20. For example, according to a preferred operation mode, assuming that solid-liquid transition temperature of the phase transition heat storage phase change material is Th, the temperature detected by temperature sensor 19 is T1, then:

-   -   When T1<Th−ΔT1, solenoid valve 31 is at work, blower 33 is         turned off, air source condenser D does not work, and the entire         heat of the system is used to heat up heat storage phase change         material 20. ΔT1 is a subcooling degree, which can be determined         by user based on experience of usage and/or preferance but         cannot be smaller than or equal to 0.     -   When T1≧Th+ΔT2, the heat storage phase change material is         entirely melted at this time, solenoid valve 31 is turned off,         blower 33 is turned on to operate, and the refrigerant may         dissipate heat to the atmosphere by the fin-tube exchanger 34.         ΔT2 is an superheating degree, which can be determined by user         based experience of usage and/or preferance but cannot be         smaller than or equal to 0.     -   When Th−ΔT1≦T1<Th+ΔT2, the states of operation of solenoid valve         31 and blower 33 are kept unchanged.

As such, by controlling the state of operation of air source condenser D, the temperature of heat storage phase change material 20 can be controlled to be kept always within a predetermined temperature range, that is, it is ensured that the high pressure the heat pump system is not too high and is always kept in a predetermined range. When the temperature of heat storage phase change material 20 detected by temperature sensor 19 is higher than an upper limit, or when the user needs not hot water, solenoid valve 28 can work and refrigerant vapor is bypassed. Release of heat by condensation of refrigerant is carried out completely by air source condenser D.

Similarly, both cold storage sub-system H and air source evaporator I in the heat pump system absorb heat from outside and carry the cold load of the heat pump system; thus, the two sub-systems may work either simultaneously or at different times. When solenoid valve 49 is at work under the control of a controller, refrigerant is bypassed and arrives at tee joint 48 from tee joint 50 without passing the tube of fin-tube heat exchanger 51 (an solenoid valve can also be provided at the inlet of the fin-tube heat exchanger 51 to completely cut-off this pathway;) at this time, air source evaporator I does not operate, and it is not necessary for blower 52 to operate.

The time at which air source evaporator I begins to operate can be determined by the temperature of cold storage phase change material 39. For example, according to a preferred operation mode, assuming that liquid-solid transition temperature of the phase cold storage phase change material is Tc, the temperature detected by temperature sensor 42 is T2, then:

-   -   When T2>Tc+ΔT3, solenoid valve 49 is at work, blower 52 is         turned off, the air source evaporator I does not work, and the         entire cold load of the system is used to freeze the cold         storage phase change material 39. ΔT3 is an superheating degree,         which can be determined by user based on experience of usage         and/or preferance but cannot be smaller than or equal to 0.     -   When T2≦Tc−ΔT4, the cold storage phase change material is         entirely solidified at this time, solenoid valve 49 is turned         off, blower 52 is turned on to operate, and the refrigerant may         absorb heat from the atmosphere by fin-tube heat exchanger 51.         ΔT4 is an subcooling degree, which can be determined by user         based experience of usage and/or preferance but cannot be         smaller than or equal to 0.     -   When Tc−ΔT4<T2≦Tc+ΔT3, the states of operation of solenoid valve         49 and blower 52 are kept unchanged.

As such, by controlling the state of operation of air source evaporator I, the temperature of cold storage phase change material 39 can be controlled to be always within a predetermined temperature range, that is, it is ensured that the low pressure of the heat pump system is not too low and is always kept within a predetermined range. When the temperature of cold storage phase change material 48 detected by temperature sensor 42 is lower than a temperature limit, or when the user needs not cold water, solenoid valve 36 can work and refrigerant is bypassed. Absorption of heat is carried out completely by air source evaporator I.

According to a preferred embodiment of the invention, a high pressure sensor 4 is provided in the high pressure pipe line of the system and a low pressure sensor 5 is provided in the low pressure pipe line of the system. when an over-high pressure or an over-low pressure is detected, operation of all compressors and blowers is stopped to ensure safety of the system.

According to a preferred embodiment of the invention, safety valves 18 and 47 are provided on heat storage tub 17 and cold storage tub 38 respectively. When the pressure of heat or cold storage phase change material in a container is too high due to over-high temperature and/or expansion of volume, the safety valves open automatically to release part of the material so as to lower the pressure within the container, thereby further inhancing the safety of the system.

It is understood by those skilled in the art that although a DC compressor sub-system A and an AC compressor sub-system B connected in parallel are arranged in the above-described embodiments, even if AC compressor sub-system B and AC power supply sub-system J are removed from the system, the system is still a photovoltaic DC driven heat pump system with cold and heat storage that is independent of any auxiliary power supply and is capable of independent operation and can be used in movable situation.

While described above is specific embodiment of the present invention, it does not limit the scope of protection of the present invention. All equivalent changes, replacement and etc. are within the scope of protection of the invention. 

1. A solar photovoltaic-commercial electricity dually driven heat pump system with cold/heat storage, characterized by comprising: a compressor module including a DC compressor sub-system (A); a photovoltaic DC power source sub-system (K) for supplying power to said DC compressor sub-system (A); an air source condenser (D); a throttle device (G); an air source evaporator (I); a heat storage sub-system (C) coupled between said compressor module and said air source condenser (D), wherein said heat storage sub-system (C) contains heat storage phase change material (20) for absorbing heat from refrigerant; a cold storage sub-system (H) coupled between said throttle device (G) and said air source evaporator (I), wherein said cold storage sub-system (H) contains cold storage phase change material (39) for being frozen by said refrigerant; wherein said compressor module, said heat storage sub-system (C), said air source condenser (D), said cold storage sub-system (H), said throttle device (G), and said air source evaporator (I) form into a loop by pipe lines, for allowing refrigerant to circulate in said loop.
 2. A heat pump system with cold and heat storage of claim 1, characterized in the said compressor module further comprises an AC compressor sub-system (B) connected in parallel with the said DC compressor sub-system (A).
 3. A heat pump system with cold and heat storage of claim 2, characterized in the four solenoid valves (1, 3, 7, 9) are provided in said compressor module for controlling the state of connection in said loop of refrigerant circulation of a DC compressor (2) in said DC compressor sub-system (A) and an AC compressor (8) in said AC compressor sub-system (B).
 4. A heat pump system with cold and heat storage of claim 1, characterized in the said heat storage sub-system (C) comprises: a heat storage container (17) with good thermal insulation containing said heat storage phase change material (20) therein; a first coil heat exchanger (23) provided within said heat storage container (17) and being connected in said loop of refrigerant circulation, for allowing refrigerant in said first coil heat exchanger (23) to exchange heat with said heat storage phase change material (20); and a second coil heat exchanger (26) provide in said heat storage container (17), for allowing water flowing through said second coil heat exchanger (26) to exchange heat with the heat storage phase change material (20) inside said heat storage container (17), said cold storage sub-system (H) comprises: a cold storage container (38) having good thermal insulation, for containing cold storage phase change material (39); a third coil heat exchanger (46) provided in said cold storage container (38) and being connected in said loop of refrigerant circulation, for allowing refrigerant in said third coil heat exchanger (46) to exchange heat with said cold storage phase change material (39); and a forth coil heat exchanger (43) provided in said cold storage container (38), for allowing water flow through said forth coil heat exchanger (43) to exchange heat with the cold storage phase change material (39) in said cold storage container (38).
 5. A heat pump system with cold and heat storage of claim 1, characterized by further comprising: a first solenoid valve (31) for bypassing said refrigerant so that said refrigerant does not go through said air source condensor (D); a second solenoid valve (49) for bypassing said refrigerant so that said refrigerant does not go through said air source evaporator (I) wherein each of said first solenoid valve (31) and said second solenoid valve (49) is provided in said refrigerant circulation loop.
 6. A heat pump system with cold and heat storage of claim 5, characterized by a first temperature sensor (19) is provided in said heat storage sub-system (C) for detecting the temperature of said heat storage phase change material (20), so as to determine the working statuses of said first solenoid valve (31); and a second temperature sensor (42) is provided in said cold storage sub-system (H) for detecting the temperature of said cold storage phase change material (39), so as to determine the working statuses of said second solenoid valve (49).
 7. A heat pump system with cold and heat storage of claim 1, characterized in the said heat storage phase change material (20) can be one selected from paraffin, hydrated salt, and sodium sulfate decahydrate, and said cold storage phase change material (39) can be one selected from glycerol, water, hydrated salt, and paraffin.
 8. A heat pump system with cold and heat storage of claim 1, characterized in that a third solenoid valve (28) for bypassing said refrigerant so that said refrigerant does not go through said heat storage sub-system (C), and a forth solenoid valve (36) for bypassing said refrigerant so that said refrigerant does not go through said cold storage sub-system (H), wherein each of said third solenoid valve (28) and said forth solenoid valve (36) is provided in said refrigerant circulation loop.
 9. A heat pump system with cold and heat storage of claim 1, characterized in that said photovoltaic DC power source sub-system (K) comprises a solar cell assembly (60), a junction box (59), a storage battery (58), and a power and voltage regulator (57).
 10. A heat pump system with cold and heat storage of claim 1, characterized in that a high pressure sensor (4) is provided in the high pressure pipe line of said system, a low pressure sensor (5) is provided in the low pressure pipe line of the system, and safety valves (18, 47) are provided in said heat storage sub-system (C) and said cold storage sub-system (H). 